How do we draw a line in our decision making process between trained intuition and careless assumption?

Sometimes, an expert medical doctor makes a dazzlingly accurate diagnosis in a complex case that baffles other physicians, yet cannot explain how she knows what ails the patient. In other cases, a doctor with similar or greater expertise might miss the diagnostic mark entirely.

It’s natural and human for a skilled practitioner to make some decisions purely on instinct. We have trained our instincts through increasing experience and craft. But if we fool ourselves into believing that we can operate on instinct alone, we can lapse into a state like unconsciousness, as if we were walking in our sleep.

To avoid the rigid mindset of sleepwalkers and the potentially terrible mistakes that could result, testers have to question everything. We especially have to question our own assumptions.